1. Field of the Invention
The present invention relates to a coding/decoding apparatus for pictures, sounds, data, etc., and more particularly to a coding/decoding apparatus with an improved circuit for detecting errors in data which have occurred in a compression division or between the compression division and an error correcting division at the sending end, by a receiving unit.
2. Description of the Prior Art
Data compressing/decompressing apparatuses for transmission according to the prior art are designed, as illustrated in FIG. 4, so that error correcting circuits 4 and 5 according to Viterbi, Reed-Solomon, etc., which are mounted in a coding unit 1 and a decoding unit 2, detect an error which has occurred in a transmission line B.
In addition, since errors which have occurred in a compressing division 3 and the interface between the compressing division 3 and an error correcting division 4 in the coding unit 1 cannot be detected by the error correcting division 5 in the decoding unit 2, conventionally, cyclic signals are inserted into an inputted original picture signal or the like which is then compressed through the coding unit 1, and the decoding unit 2 which has received the compressed data decompresses the data in a decompressing division 6, and verifies the data to detect an error.
As mentioned above, with a coding/decoding apparatus of the prior art, original data with cyclic signals are inserted therein undergoes data compression according to variable length coding, and the decoded data is verified in the decoding unit to detect an error.
This mechanism, however, has a problem in that error-mixed data, even once processed by decompression, may cause the cyclic data to be produced depending on the contents of the data, and thus detection of errors may become impossible. In addition, since errors can be detected only at intervals of reception of the cyclic data, errors cannot be detected in early stages.